Base Set 2-Player starter set sells ~$4k
Released in 1999 by Wizards of the Coast as part of the original Base Set era of the Pokémon Trading Card Game, the two-player starter set included two half-decks of 30 cards each, a rulebook, damage counters, and everything needed to play right out of the box. A standout feature was the holographic Machamp card, which was exclusive to this set and not found in standard booster packs. Prices have doubled since July where sold listings were around $1.5k-$2k (this doesn’t account for the first release versions).
Fun fact: every single Machamp from this product was printed as a 1st Edition card, making it one of the most common 1st Edition holos ever produced (non-shadowless version). Only the first release of this set includes the Shadowless copies of the Machamp card.